Di-schiff bases of hydroxyl substituted diamines and beta-diketones, derivatives, and metal chelates thereof



United States Patent 3,388,141 DI-SCHIFF BASES OF HYDROXYL SUBSTITUTEDDIAMINES AND B-DKKETONES, DERIVATIVES, AND METAL CHELATES THEREOF MorrisB. Berenbaum, Levittowu, Pa., assignor to Thiokol Chemical Corporation,Bristol, Pa., a corporation of Delaware No Drawing. Filed Oct. 5, 1965,Ser. No. 493,216 13 Claims. (Cl. 260439) ABSTRACT OF THE DISCLOSURE Thedi-Schiff base of a fl-hydroxy-1,3-diamine and a 1,3-diketone arecapable of chelating a large number of heavy metal ions. These metalchelates function as burning rate modifiers when incorporated inpropellant compositions.

This invention relates to new chelate complexes and to their preparationand use as a means of modifying the burning rate properties of solidpropellant compositions.

Liquid, curable, polymeric materials are used in the rocket arts asbinders to prepare propellant fuels therewith. The liquid, curablepolymeric materials are blended with the other ingredients of theproposed fuel composition which includes a curing agent for the liquidpolymers, oxidizers, fillers and burning rate modifiers and theresulting composition is then subjected to the necessary cure conditionswhich will cause the liquid polymer to react with the curing agent toform a solid fuel matrix comprising the cured polymer and the variousother ingredients of that fuel randomly dispersed therein. It isessential that the various components of the solid fuel system be evenlydistributed to avoid imparting erratic firing properties to the fuelmatrix. Because of the relatively viscous nature of the uncured systemsand the relatively large sized batches of the systems usually preparedat one time on a commercial basis it is very dificult, if notimpossible, to readily obtain a uniform dispersion of the componentsthroughout the system.

An object of the present invention is to provide monomeric polymerizablechelates which may be used to modify the burning rate properties ofsolid propellant compositions made therewith.

Another object of this invention is to provide means for modifying theburning rate properties of polymeric propellant binder materials bychemically incorporating monomeric chelate materials in the polymericbinder materials.

A further object is to provide novel and useful intermediates forpreparing monomeric polymerizable chelates useful as burning ratemodifiers in solid propellant compositions.

Still another object of this invention is to provide novel chelatecontaining polymers.

It has been unexpectedly found, according to the present invention thatthe burning rate properties of a propellant composition or matrix can bereadily and reproducibly regulated if the polymeric binder used in thefabrication of the matrix is formed, in part, from one or moremonomeric, polymerizable chelates having the structure where R and Reach represent either hydrogen or a lower alkyl group, R representseither hydrogen, acryloyl, methacrylolyl, vinyl or isopropenyl, R and Reach represent a lower alkyl group, and M represents a heavy metal suchas iron, nickel, cobalt, copper, cadmium, zinc, lead and manganese. Thechelate moieties act as the burning rate modifiers for the propellantcomposition and the desired burning rate characteristics can be readilyand reproducibly imparted to the propellant matrix by regulating theamount and type of chelate incorporated in the polymeric binder. Beingan integral component of the liquid polymer binder, the chelate burningrate modifiers of the present invention are readily dispersed,uniformly, throughout the propellant matrix.

The polymerizable monomeric chelates which are usefully employed asburning rate controlling components of solid propellant fuels accordingto the present invention are prepared by a three-step process accordingto Equations 1, 2 and 3, shown below.

A fi-hydroxyl-LB-diamine is first reacted with 2 moles of a 1,3-diketonein a solvent medium such as ethanol to form a di-Schifi base R CH(NH)CH(OH)CH(NH )R (Equation '1) in which R and R each represent eitherhydrogen or a lower alkyl group, and R and R each represent a loweralkyl group.

The di-Schitf base, sodium hydroxide, and sodium acetate is thendissolved in boiling water and reacted with a soluble salt of a heavymetal.

(Equation 2) 11I lii,388,l41

3 The chelate thus produced is then further esterified to form anacrylic ester thereof through its reaction with acrylyl chloride intriethylamine or acrylic anhydride:

R4 R5 is 0 .Acrylyl chloride in triethylamine HO M Acrylic anhydride N Om The extreme insolnbility of this class of metal chelates in water andin organic solvents of all types necessitates the conduction of theesterification reaction under heterogeneous conditions.

In preparing the curable, polymeric binder materials according to thepresent invention the polymerizable, monomeric chelates disclosed aboveare copolymerized with one or more of the monomeric materialscustomarily employed to form such binder materials. The monomericmaterials include diene and vinyl type monomers such as butadiene,acrylic acid and methacrylic acid. The polymerization reaction may becarried out in bulk or in solution using either free radical or ionictype initiators such as azobisisobutyronitrile. Where abutadiene/acrylic acid/chelate system is being polymerized the lessreactive member, butadiene, is added all at once initially and the morereactive members of the system, acrylic acid and the chelate are addedintermittently during the course of the reaction to maintain the ratioof monomers needed to produce a polymer having the desired monomercontent. Where the chclate is a solid it may be added to thepolymerization system when dissolved in an organic solvent such asbenzene.

The molecular weight of the resulting polymer, moreover, can beregulated with a chain transfer agent such as t-dodecylmercaptan. Byusing the proper ratio of monomers to chain transfer agents, liquidpolymers of predetermined viscosities can be obtained. Liquid polymersare preferred because of the relative ease of blending them with theother components of the fuel system.

At the termination of the reaction the polymers are readily recoveredfrom the unreacted monomeric material either by evaporating the morevolatile monomers or by washing the polymers.

The following example is merely illustrative of the present inventionand is not intended as a limitation upon the scope thereof.

Example 1 400.4 grams (4.0 moles) of 2,4-pentanedione in 500 millilitersof benzene was charged into a 2-liter threenecked fiask which wasequipped with a stirrer and a condenser and a Dean-Stark trap forremoval of water. 180.2 grams (20 moles) of2-hydroxy-L3-propylenediamine was added dropwise while stirring during20 minutes to the reaction flask. After the initial reaction hadsubsided, the admixture was heated under reflux for 4 hours. During thereflux period the theoretical amount of water (72 grams) was collectedin the water trap. On cooling the admixture tan crystals ofbis-N,N'-di(2,4- pentanedionyl)-2-hydroXy-1,3-propylene diamine productwas formed. The product was recovered by filtration, tol- 75 lowed byrecrystallization from benzene. The yield of product was 480 grams. Themelting point of the product was l04 to l05.5 C. Elemental analysis ofthe product showed 11.37% nitrogen as compared with the calculated valuefor C H O N of 11.02% nitrogen. Thebis-N,N'-di(2,4-pentanedionyl)-2-hydroxy-1,3 propylene product was driedand ground to a fine powder. This finely ground product, 15.5 grams ofsodium hydroxide and 2 grams of sodium acetate were dissolved in 600 ml.of boiling water. 55.6 grams of iron sulfate-7H O was then added whilestirring until the admixture became a paste. The mass was covered with/2 inch of water and allowed to stand for about 20 minutes. The motherliquor was then removed from the mass by means of a centrifuge leavingbehind a hard cake. This cake was dried overnight under vacuum at 58 C.to yield bis-N,N- di(2,4 pentanedionyl)-2-hydroxy1,3-propylene diamineiron chelate as a light brown, pyrophoric solid which burned to red ironoxide upon contact with air.

Analogous chelate product of othe. metals may be prepared bysubstituting for the iron sulfate-751 0 in the above reaction othermetal salts, such as, for example, nickel chloride-6H O and therespective acetate salts of cobalt, copper, cadmium, zinc, lead, andmanganese.

The acrylate ester of the iron chelate product is prepared by reactingthe iron chelate product with acrylic anhydride. A curable, polymericbinder material is prepared by copolymerizing the iron chelate productor the acrylate ester of such product with vinyl compounds such asbutadiene and acrylic acid and recovering the polymeric product.

I claim:

.1. A composition of matter having the structure -N OH in which R and Reach represent substituents selected from the group consisting ofhydrogen atoms and lower alkyl groups, and R and R each represent alower alkyl group.

2. A composition of matter according to claim 1, in which R.,, and Reach represent a methyl group.

3. A composition of matter according to claim 1, in which R; and R eachrepresent hydrogen.

4. A composition of matter having the structure in which R and R eachrepresent a substituent selected from the group consisting of hydrogenatoms and lower alkyl groups, R represents a substituent selected fromthe group consisting of hydrogen, acryloyl, methacryloyl, vinyl, andisopropenyl groups, R; and R each represents a lower alkyl group, and Mrepresents a heavy metal.

5. A composition of matter according to claim 4, in which R and Rrepresent a methyl group.

6. A composition of matter according to claim 4, in which R and R eachrepresent hydrogen. 1

7. A composition of matter according to claim 4, in which M is heavymetal selected from the group consisting of iron, nickel, cobalt,copper, cadmium, zinc, lead, and manganese.

8. A composition of matter according to claim 7, in which M is iron.

9. A composition of matter according to claim 4, in which R is hydrogen.

10. A composition of matter according to claim 4, in which R is anacryloyl group.

11. A composition of matter according to claim 4, in which R is amethacryloyl group.

12. A composition of matter according to claim 4, in which R is a vinylgroup.

13. A composition of matter according to claim 4, in which R is anisopropenyl group.

6 References Cited UNITED STATES PATENTS 4/ 1966 Berenbaum 260429 OTHERREFERENCES Holm, J. Am. Chem. Soc. 82 (1961), pp. 5632-5636.

HELEN M. MCCARTHY, Primary Examiner.

TOBIAS E. LEVOW, Examiner.

A. P. DEMERS, Assistant Examiner.

